The invention relates to a unit and a process for the decontamination of containers containing radioactive liquid.
A typical application of the invention would be in a radioactive liquid analysis installation, where radioactive samples are poured into containers. The containers have two parts, a sealing stopper and a jug. The containers are transferred through the pipes of a pneumatic transfer system from one shielded unit to another. The final destination of the containers is a unit in which their residual content is emptied, and the containers are decontaminated. Currently, containers are accumulated until a sufficiently large batch has been collected, after which, following emptying and possible crushing, they are put into a decontamination tank filled with washing liquid and are left there for several hours, after which they are recovered and stored. The current means of decontamination does not sufficiently decontaminate the containers and under existing standards the containers must be buried in bitumen, concrete or glass drums at a great depth in a specialized installation. The current process is expensive, occupies a considerable volume and may become impermissible if stricter reprocessing standards are adopted.
The ultimate aim of the invention is to improve the reprocessing characteristics of spent containers. This requires that decontamination take place rapidly following the filling of the container with the liquid to be sampled and analyzed, e.g. one hour afterwards, which is possible in numerous cases by rapidly performing the sampling operations and the measurements. It has in fact been found that the adsorption or incrustation of contaminating solutes of the liquid on the plastic wall of the container was not completed after this brief period, whereas it is irreversible after one or two days. This lengthy waiting time is typical of existing installations. The benefit of a rapid decontamination is a limited residual contamination of the containers, which makes it possible to store them, at a much lower cost and with fewer constraints, in surface facilities.
It has also been found that the crushing of polluted containers prior to decontamination increases the incrustation of contaminants. Therefore, the invention decontaminates the containers prior to crushing by carefully washing the containers, which is made possible without using a large quantity of washing liquid, e.g. less than 100 to 200 ml per container. Crushing takes place on decontaminated containers making it possible to reduce their volume in the drums or storage canisters without any prejudicial effect resulting therefrom.